1. The Field of the Invention
The present invention relates to orthodontic brackets that include a bracket base and at least one slot for receiving an arch wire as well as a feature for early torque control.
2. The Relevant Technology
Orthodontics is a specialized field of dentistry that involves the application of mechanical forces to urge poorly positioned, or crooked, teeth into correct alignment and orientation. Orthodontic procedures can be used for cosmetic enhancement of teeth, as well as medically necessary movement of teeth to correct overjets or overbites. For example, orthodontic treatment can improve the patient's occlusion, or enhanced spatial matching of corresponding teeth.
The most common form of orthodontic treatment involves the use of orthodontic brackets and wires, which together are commonly referred to as “braces.” Orthodontic brackets, more particularly the orthodontic bases, are small slotted bodies configured for direct attachment to the patient's teeth or, alternatively, for attachment to bands which are, in turn, cemented or otherwise secured around the teeth. Once the brackets are affixed to the patient's teeth, such as by means of glue or cement, a curved arch wire is inserted into the slot of each bracket. The arch wire acts as a template or track to guide movement of the teeth into proper alignment.
There are two distinct classes of orthodontic brackets: those that require the use of ligatures to fasten the arch wire to the bracket, and those that are self-ligating. In brackets of the first class, small ligature wires or elastics are typically used to hold the arch wire in a securely seated position in the brackets. Ligatures or some other form of fastening means are essential to ensure that the tensioned arch wire is properly positioned around the dental arch, and to prevent the wire from being dislodged from the bracket slots during chewing of food, brushing of teeth, or application of other forces. One type of commercially available ligature is a small, elastomeric O-ring, which is installed by stretching the O-ring around small wings known as “tie wings” that are connected to the bracket body. Metal ligatures are also used to retain arch wires within the bracket slots.
In an effort to simplify the process of installing braces, a variety of self-ligating brackets have been developed. The term “self-ligating bracket” refers to a class of orthodontic brackets that include some sort of cover, whether separate from, hingedly or otherwise attached to the base, which encloses or otherwise retains the arch wire within the slot of the base.
In either case, there is a need during treatment to apply various corrective forces to the teeth during treatment. Arch wires having different cross-sectional configurations are typically used to apply different forces, depending on the corrective movement to be achieved. Arch wires typically have either a square, rectangular, or round cross-section. Square and rectangular cross-sections allow the arch wire to be used to apply a torquing force when engaged in an arch wire slot of an orthodontic bracket. Torquing forces provide for tooth movement in the labial and/or lingual directions. Although a wire having a round cross-section does not allow application of torquing forces when engaged within an arch wire slot, it does provide a greater degree of flexibility and generally requires less force to effect movement, which is more comfortable for the patient. As such, round wires are often useful during the beginning stages of orthodontic treatment when the teeth are most malaligned. Use of such a round arch wire allows for movement of teeth to correct spacing and alignment issues with relatively light (and more comfortable) forces. Once these corrections have been achieved, a square or rectangular wire typically replaces the round arch wire, so as to allow torquing of selected teeth to complete the treatment.
As such, treatment often progresses in a series fashion, in which spacing and alignment issues are first addressed, and tooth movement in the labial and/or lingual directions is addressed afterwards. Although such treatment regimes work, they can take several months to complete. As such, it would be an improvement in the art to provide an orthodontic bracket which could be easily manufactured, and which would include a mechanism for allowing application of relatively light forces (i.e., similar to those applied by a round arch wire), but which forces are also capable of applying a corrective torquing force. Such a bracket would be expected to provide movement of teeth to correct spacing and alignment with light forces, while simultaneously providing torquing movements, which would provide for faster overall treatment times, while also providing increased comfort for the patient during torquing correction.